Poor Service Received & System / Data Limitation

My name is Lydia Mako Id number *** 082, I will start by thanking Vodacom with my service received during my term of contract I didn't have any problems for 24 months. The problem just started after my contract ended with the number *** contract ended on the 26.06.2015. I want to lodge a complaint on the service that I have received from Vodacom. I received the sms that confirm that my phone number has been changed to prepaid, I bought a R80 airtime and change to 1GB data for 30 days, the last time I checked my data balance on the 29.06.2016 I had about 819 MB available then on the 30.06.2015 I received the sms from Vodacom stated that my 1GB has been changed to recurring data. I checked the balance It was zero balance available ,my data was depleted. , then I was impatience because they were giving me different answers .Then I was frustrated again I called Vodacom Call centre, the lady by the name Mbali told me that I must not transfer airtime , I then bought R70 airtime to the number *** and I received the sms that states I can buy the data for R69 for 7 days which I did buy still my data was zero until now. Please advise me..... on what to do?